diff --git a/src/Umbraco.Core/Models/PublishedContent/PublishedContentType.cs b/src/Umbraco.Core/Models/PublishedContent/PublishedContentType.cs
index de54132e2c..676c3366ac 100644
--- a/src/Umbraco.Core/Models/PublishedContent/PublishedContentType.cs
+++ b/src/Umbraco.Core/Models/PublishedContent/PublishedContentType.cs
@@ -13,6 +13,7 @@ namespace Umbraco.Core.Models.PublishedContent
     public class PublishedContentType
     {
         private readonly PublishedPropertyType[] _propertyTypes;
+        private readonly HashSet<string> _compositionAliases;
 
         // fast alias-to-index xref containing both the raw alias and its lowercase version
         private readonly Dictionary<string, int> _indexes = new Dictionary<string, int>();
@@ -24,7 +25,7 @@ namespace Umbraco.Core.Models.PublishedContent
         {
             Id = contentType.Id;
             Alias = contentType.Alias;
-            CompositionAliases = contentType.CompositionAliases();
+            _compositionAliases = new HashSet<string>(contentType.CompositionAliases(), StringComparer.InvariantCultureIgnoreCase);
             _propertyTypes = contentType.CompositionPropertyTypes
                 .Select(x => new PublishedPropertyType(this, x))
                 .ToArray();
@@ -36,7 +37,7 @@ namespace Umbraco.Core.Models.PublishedContent
         {
             Id = id;
             Alias = alias;
-            CompositionAliases = compositionAliases;
+            _compositionAliases = new HashSet<string>(compositionAliases, StringComparer.InvariantCultureIgnoreCase);
             _propertyTypes = propertyTypes.ToArray();
             foreach (var propertyType in _propertyTypes)
                 propertyType.ContentType = this;
@@ -62,7 +63,7 @@ namespace Umbraco.Core.Models.PublishedContent
 
         public int Id { get; private set; }
         public string Alias { get; private set; }
-        public IEnumerable<string> CompositionAliases { get; private set; }
+        public HashSet<string> CompositionAliases { get { return _compositionAliases; } }
 
         #endregion
 
diff --git a/src/Umbraco.Tests/Umbraco.Tests.csproj b/src/Umbraco.Tests/Umbraco.Tests.csproj
index 537ace8c23..e553be9b49 100644
--- a/src/Umbraco.Tests/Umbraco.Tests.csproj
+++ b/src/Umbraco.Tests/Umbraco.Tests.csproj
@@ -427,9 +427,7 @@
     <Compile Include="PublishedContent\PublishedContentDataTableTests.cs" />
     <Compile Include="PublishedContent\PublishedContentTestBase.cs" />
     <Compile Include="PublishedContent\PublishedContentTestElements.cs" />
-    <Compile Include="PublishedContent\PublishedContentTests.cs">
-      <ExcludeFromStyleCop>True</ExcludeFromStyleCop>
-    </Compile>
+    <Compile Include="PublishedContent\PublishedContentTests.cs" />
     <Compile Include="PublishedContent\PublishedMediaTests.cs" />
     <Compile Include="HashCodeCombinerTests.cs" />
     <Compile Include="Web\Mvc\HtmlHelperExtensionMethodsTests.cs" />
@@ -760,7 +758,7 @@
 xcopy "$(ProjectDir)"..\packages\SqlServerCE.4.0.0.1\x86\*.* "$(TargetDir)x86\" /Y /F /E /I /C /D</PreBuildEvent>
   </PropertyGroup>
   <Import Project="$(SolutionDir)\.nuget\nuget.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
+  <!-- To modify your build process, add your task inside one of the targets below and uncomment it.
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">
   </Target>